About IES Solver Methods
Boundary Element Method (BEM)
The Boundary Element Method solves field problems by solving an equivalent source
problem. In the case of electric fields it solves for equivalent charge, while in the case of
magnetic fields it solves for equivalent currents.
BEM also uses an integral formulation of Maxwell's Equations, which allow for very highly
accurate field calculations. The formulations are such that differentiating the field is
not a problem.
Finite Element Method (FEM)
Finite elements solve by breaking up a problem into small regions and solutions are found for
each region taking into account only the regions that are right next to the one being solved.
In the case of magnetic fields where FEM is often used, the vector potential is what is solved
for in these regions.
Magnetic field solutions are derived from the vector potential through differentiating the
solution. This can cause problems in smoothness of field solutions. Theoretically, any partial
differential equation class of problem can be solved using FEM (although some types
will do better than others.)
Hybrid BE-FE Method
When you compare the advantages and disadvantages (below), you can see that an ideal method
would be to combine both methods to form a hybrid of the two.
The hybrid solver takes the strengths of both methods and uses
them to an advantage.
The BEM handles the open regions and linear solution while
the FEM handles the non-linear areas.
The results are excellent open region solutions with no
non-linear convergence problems.
BEM and FEM: A Comparison
BEM Advantages |
FEM Advantages |
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Open regions not a problem
Extreme aspect ratios not a problem
World space is not truncated
Perfectly smooth field solutions |
Non linear problems easily solved
Easy formulations allow many different types of problems to be
solved |
BEM Disadvantages |
FEM Disadvantages |
Non linear problems difficult to solve
Some problem formulations are not possible
|
Not well suited for open region problems
Extreme aspect ratios can cause problems
Truncated world space
Fields can be noisy
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For a more in depth analysis of BEM, FEM and the Hybrid BE-FE Method
see A Hybrid Magnetic Field Solver Using a Combined
Finite Element/Boundary Element Field Solver.
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"I truly enjoy using IES software. Its combination of speed, accuracy and extraordinary
user-friendliness make my work much more productive. I would like to thank the IES team for
an excellent numerical code."
Dr. Valery Rudnev
Inductoheat Group
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